Student Lab 1: Input, Processing, and Output



Lab 3: Decisions and Boolean Logic

This lab accompanies Chapter 4 of Starting Out with Programming Logic & Design.

branden and alex

Name: ___________________________

Lab 3.1 – Evaluating Conditions

|Critical Review |

| |

|A relational operator determines whether a specific relationship exists between two values. |

| |

|Relational operators |

|Operator |

|Meaning |

|Boolean Expression |

| |

|> |

|Greater than |

|X > Y |

| |

|< |

|Less than |

|X < Y |

| |

|>= |

|Greater than or equal to |

|X >= Y |

| |

| myAge |false |

|myAge == 45 |false |

|yourAge == votingAge |true |

|votingAge =80 Then |“my number is 80 or more” |

|print “My number is 80 or more” | |

|End If | |

|If yourNumber = votingAge Then |“you can vote” |

|print “You can vote” | |

|End If | |

|If myAge < yourAge Then |Nothing |

|print “I am younger” | |

|End If | |

Lab 3.2 – Pseudocode and Decisions

This lab requires you to think about the steps that take place in a program by writing pseudocode. Read the following program prior to completing the lab.

A retail company assigns a $5000 store bonus if monthly sales are $100,000 or more. Additionally, if their sales exceed 125% or more of their monthly goal of $90,000, then all employees will receive a message stating that they will get a day off.

Step 1: This program is easiest when solved using just one variable. Declare the variables that you will need in the program, using the proper data type and documenting the purpose. Depending on your programming style, you may find additional variables are useful. If that is the case, adjust your program as necessary.

|Variable Name |Purpose |

|“bank” |Stores the monthly sales |

| | |

Step 2: Given the major task involved in this program, what modules might you consider including? Also describe the purpose of the module.

|Module Name |Purpose |

|Module getSales () |Allows the user to enter the monthly sales. |

|Module isBonus() |This module will determine if a bonus should be awarded. |

|Module dayOff() |This module will determine if a day off should be awarded. |

Step 3: Complete the pseudocode by writing the missing lines. When writing your modules and making calls, be sure to pass necessary variables as arguments and accept them as reference parameters if they need to be modified in the module. (Reference: Writing a Decision Structure in Pseudocode, page 118).

Module main ()

//Declare local variables

Declare Real monthlySales

//Function calls

Call getSales(monthlySales)

Call isBonus(determines if a bonus is awarded)

Call dayOff(determines if a day off shall be given)

End Module

//this module takes in the required user input

Module getSales(Real Ref monthlySales)

Display “Enter the total sales for the month.”

Input monthlySales

End Module

//this module will determine if a bonus is awarded

Module isBonus(Real Ref monthlySales)

If monthlySales >=100000 Then

Print “You get a bonus of $5,000!!!”

End If

End Module

//this module will determine if all employees get a day

//off. If sales are greater than or equal to 112500, then

//they get a day off.

Module dayOff(Real Ref monthlySales)

______________________________________________________

If the monthly sales exceed 112500 then they get a day off

______________________________________________________

______________________________________________________

End Module

Lab 3.3 – Flowcharts

This lab requires you to convert your pseudocode in Lab 3.2 to a flowchart. Use an application such as Raptor or Visio.

Step 1: Start Raptor and save your document as Lab 3-3. The .rap file extension will be added automatically. Start by adding a Comment box that declares your variables. Here is how your Comment box should look.

[pic]

Step 2: The next step in your flowchart should be to call your methods. Below is a start of how your main should look.

[pic]

Step 3: Continue this process to add your additional methods you defined in Lab 3.2, Step 3.

Step 4: Click on the getSales tab and add the necessary code to enter the monthly sales. Your getSales method might look like the following:

[pic]

Step 5: Click on the second module which determines if a bonus of $5000 is awarded. Click the Selection symbol and add it between the start and the end of the module. Double click on the diamond symbol and add the code to determine if monthlySales is greater than or equal to 100000. The enter selection condition should be written as follows:

[pic]

Step 6: Drag an output symbol and drop it on the True line. Double click on the output box and add text that prints “You earned a $5000 bonus!”. Your module should like as follows:

[pic]

Step 7: Repeat the process in Step 6 to code your next module.

Step 8: When your program is complete, test the following monthly sales and ensure that the output matches the following. If your output is different, then review your decision statements.

|Monthly Sales |Expected Output |

|monthlySales = 102500 |You earned a $5000 bonus! |

|monthlySales = 90000 | |

|monthlySales= 112500 |You earned a $5000 bonus! |

| |All employees get one day off!!! |

Step 9: The final step is to insert your finished flowchart in the space below. Inside Raptor, select File and the Print to Clipboard from the menu. Inside Word in the space below, select Edit and Paste. You will have to do this for each module you created.

[pic]

[pic][pic]

[pic]

Lab 3.4 – Python Code

Step 1: Start the IDLE Environment for Python. Prior to entering code, save your file by clicking on File and then Save. Select your location and save this file as Lab3-4.py. Be sure to include the .py extension.

Step 2: Document the first few lines of your program to include your name, the date, and a brief description of what the program does. Description of the program should be:

#This program will demonstrate how to use decision

#statements in Python.

Step 3: Start your program with the following code:

#This program determines if a bonus should be awarded

#The main function

def main():

print 'Welcome to the program'

monthlySales = getSales() # gets sales

#This function gets the monthly sales

def getSales():

monthlySales = input('Enter the monthly sales $')

monthlySales = float(monthlySales)

return monthlySales

#calls main

main()

Step 4: Add a function call to the method that determines if a bonus is awarded. The call should be in main and process after monthlySales = getSales(). Be sure to pass monthlySales to the function as an argument since that will be needed to determine if a bonus is awarded. Your code might look as follows:

#Function call to determine bonus

isBonus(monthlySales)

Step 5: Under the getSales() function, code the function that will determine if a bonus is awarded. Be sure to accept monthlySales in the parameter list. Also, note that the if statement is followed by a colon, and the print statement inside must be tabbed over.

def isBonus(monthlySales):

if monthlySales >= 100000:

print "You have earned a $5,000 bonus!!!"

Step 6: Repeat the process in Step 4 to make a function call to the method that determines if all employees get a day off.

Step 7: Repeat the process in Step 5 to code the function that will determine if all employees should get a day off.

Step 8: Click Run and Run Module to see how your program processes. Test the following monthlySales values to verify the expected output.

|Monthly Sales |Expected Output |

|monthlySales = 102500 |You earned a $5000 bonus! |

|monthlySales = 90000 | |

|monthlySales= 112500 |You earned a $5000 bonus! |

| |All employees get one day off!!! |

Step 9: Execute your program so that it works and paste the final code below

#This program will demonstrate how to use decision #statements in python

#This program determines if a bonus should be awarded

#The main function

def main():

print 'Welcome to the program'

monthlySales = getSales() #gets sales

isBonus(monthlySales)

#This function gets the monthly sales

def getSales():

monthlySales = input('Enter the monthly sales $')

monthlySales = float(monthlySales)

return monthlySales

def isBonus(monthlySales):

if monthlySales >= 100000:

print 'You have earned a $5000 bonus!!!'

#calls main

main()

Lab 3.5 – Programming Challenge 1 – Guess the Secrets

Write the Pseudocode, Flowchart, and Python code for the following programming problem.

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Guess the Secrets

Write a program that will ask the user to enter a person’s age, their weight, and their birth month. Your program will compare the entered values to the following and print the appropriate responses. Be sure to use modules.

|The Secret Answers |The Comparison |The Printed Response |

|age = 25 |If the guessed age is less than or |Congratulations, the age is 25 or less |

| |equal to 25 | |

|weight = 128 |If the guessed weight is greater than |Congratulations, the weight is 128 or more |

| |or equal to 128 | |

|birthMonth = ‘April’ |If the guessed birth month is equal to |Congratulations, the birth month is April |

| |April | |

Hint: This program can be written a few different ways. It is suggested that only three variables are used to store the guessed answers to age, weight, and birthMonth. The pseudocode for main might look as follows:

Module main ()

//Declare local variables

Declare Integer age

Declare Integer weight

Declare String birthMonth

//Function calls

Call getAge(age)

Call getWeight(weight)

Call getMonth(birthMonth)

Call correctAnswers(age, weight, birthMonth)

End Module

If the program is written properly, sample output should look as follows:

Sample 1:

//Input

Enter your guess for age: 20

Enter your guess for weight: 140

Enter your guess for birth month: March

//Output

Congratulations, the age is 25 or less.

Congratulations, the weight is 128 or more.

Sample 2:

//Input

Enter your guess for age: 32

Enter your guess for weight: 119

Enter your guess for birth month: April

//Output

Congratulations, the birth month is April.

Sample 3:

//Input

Enter your guess for age: 58

Enter your guess for weight: 128

Enter your guess for birth month: January

//Output

Congratulations, the weight is 128 or more.

The Pseudocode

Module main()

//declare local variables

Declare integer Age

Declare integer weight

Declare string birthMonth

//Function calls

Call getAge(age)

Call getWeight(Weight)

Call getMonth (birthMonth)

Call correctAnswer(age, weight, birthMonth)

End module

//module for getAge

Display “Enter the age”

End module

//module for getweight

Display “guess for weight”

End module

//module for getMonth

Display “guess for birth month”

End module

//module for correctAnswer(integer Age, interger weight, string birthMonth)

if age is =128

Display “congratulations the guessed weight is 128 or more”

End if

if birth month is == April

Display “congratulations the birth month is April”

End if

End module

The Flowchart

[pic][pic][pic][pic][pic]

The Python Code

def main():

age = getAge()

weight = getWeight()

birthMonth = getMonth()

print

correctAnswers(age, weight, birthMonth)

#this function will input the age

def getAge():

age = input('Enter your guess for age: ')

return age

#function for getWeight

def getWeight():

weight = input('Enter your guess for weight: ')

return weight

#function for getMonth

def getMonth():

birhtMonth = input('Enter your guess for birth month: ')

return birthMonth

#function for determining if answer are correct

def correctAnswer(age, weight, birhtMonth):

if age =128:

print 'Congratualtions, the weight is 128 or more.'

if birthMonth == 'April':

print "congratualtions, the birth month is April"

#calls main

main()

-----------------------

Critical Review

Questions are often asked using an if statement such as if(X > Y), whereas the question asked is “is X greater than Y”?

The general structure of an if statement is

If condition Then

Statement

Statement

Etc.

End If

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Critical Review

The flowchart symbol used to indicate some condition is a diamond. An if statement is called a single alternative decision structure. The code will only process if the decision is true.

[pic]

Help Video: Double click the file to view video

Critical Review

In Python we use the if statement to write a single alternative decision structure. Here is the general format of the if statement:

if condition:

statement

statement

etc.

For simplicity, we will refer to the first line as the if clause. The if clause begins with the word if, followed by a condition, which is an expression that will be evaluated as either true or false. A colon appears after the condition. Beginning at the next line is a block of statements.

When the if statement executes, the condition is tested. If the condition is true, the statements that appear in the block following the if clause are executed. If the condition is false, the statements in the block are skipped.

When strings are evaluated in a condition, single quotation marks are used. For example:

name1 = 'Mary'

name2 = 'Mark'

if name1 != name2:

print 'The names are not the same.'

if name1 == ‘Mary’

print ‘The name is Mary.’

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